MBT: MBT reads lower methylation states, recognizing mono- and dimethylated lysines. All MBTs characterized at present contain two to four repeats of ~100 amino acids. The most common three-repeat 3MBT module folds in a propeller-like structure, and the four-repeat 4MBT module has an asymmetric rhombus architecture29-32. Notably, although each MBT repeat contains an aromatic cage, which also includes an acidic residue, only the second repeat binds methyllysine. (1)